Voltage regulator



Jan. 13, 1953 F. J. LUPO 2,625,575

VOLTAGE REGULATOR Filed March 16, 1951 2 sHEE's-smlz'r 1 l l l l l l x II N om .vm.\ m mm ATTORNEY Jan. 13, 1953 F. J. LUPO VOLTAGE REGULATOR 2 SHEETS--SHEET 2 Filed March 16, 1951 FIG. 2

m\ l|||l|| INVENTOR. FRANK J. LUPO ATTORNEY Patented Jan. 13, 1953 UNITED STATES PATENT GFFICE VOLTAGEy REGULATOR.;v

Frank J. Lupo, Hackensack, N. J'., assignor to Chatham Electronics Corporation,

Newark;

N. J., aY corporation of New 'Jersey Application March 16, 1951, SerialNo. 216,069'

' Claims.

This invention relates to voltage yregulators cfr the type which receive power-from an alternating current source and deliver direct current to a load circuit. The invention hasv particular reference to voltage regulators capable of delivering a voltage which is constant to one part in 600,000 with respect to a reference voltage source whichis used as a standard.

Electronic regulator circuits are old in the art and many different circuits have been proposed and used. The mostpopular arrangements generally employ one or more triode discharge devices in series connection between the supply` line and the load with a voltage sensitive circuit coupled between the load and control. electrode of the series tube. The voltage sensitive circuit may use a battery or a gaseous discharge tube as a reference Voltage. Such circuits regulate quite well, especially those using a battery as a reference voltage. When properly adjusted these circuits provide a compensation for voltage varia-v One of the objects of this invention is to provide an improved voltage regulator which avoids one or more of the disadvantages and limitations of prior art arrangements.

Another object of the invention is toLA deliver a constant unvarying potential to a load circuit using a controlled variable tap on a voltage divider to compensate and correct for the slow driftV caused by variable characteristics in the voltage sensitive circuit.

Another object ofthe invention is to. improve the voltage regulation in electronic regulator circuits sor that a variation of ten percent in the.

supply voltage will cause `the load voltage to vary less than one part in 600,000.

Still another object of the invention isA to improve the voltage regulation in the presence of abrupt variations in load impedance and low frequency variations in load current, thereby greatly reducing the effective internal impedance (as measured at the` output terminals) of the power supply. ImpedancesA of less thairan ohm are easily obtainable.

The invention includes. an electron discharge` device in series arrangement between the source and the load. The bias potential ofV the control electrode of the discharge device is derived fromV the output of a three stage direct current amplifier.

in turn is connected to the load terminals. A

novel feature of the invention comprises a voltage..

sensitive. circuit for detecting an error voltage,

a reference battery, an inverter system/forV con-- verting the error voltage to alternatingcurrent..

an amplifier and phase discriminator,A and a reversible motor which is coupled to theY variablek contact on the voltage divider to return the system to equilibrium andreduce the error voltage to zero.

For a. better understanding of the present invention, together with other and further objects thereof, reference is made to the following de-V scription taken in connection with the accompanying drawings.

Fig. 1 isa schematic diagram of connections showing a circuitof a voltage regulator.

Fig. 2 is a schematic diagram of`connections.

of. a part of a voltage regulator showing an alternate arrangement for connecting the input circuit of the direct current amplifier.

Fig. 3 is a curve showing the current wave shape obtainable at the mid-point ofthe transformer which supplies the anode power in the phase dis'- criminator stage when the input-tov that stage is',

Fig. 4 is a curve similar to Fig. 3"but showing.

the current wave shape when the input is other than zero.

Referring now tothe drawing, powerlines.v I0 are connected to the usual Gllcycle commercial supply. A primary II of an iron-cored transformer is connected across the power. lines and secondaries I 2 and I3 supply power to the anodesV and filament of a-rectier tube. I4. A pulsating voltage is yobtained between themid-points of the two .secondaries' and a lter I5v is employed toy eliminate the alternating components and de, liver direct current power across.v a terminal're'- sistor I6.

One or more electron tubes Il are connected in series with the positive power conductorand constitute the means for regulatingtheload voltage. The control electrodes of the series tubes Ii are connected to the anode of an amplier. tube I8 and the cathodes of the series tubes are. connected to the anode of a second,ampliiier'tubeV 20.V Amplifier tubes I8 and 2U are part oi adirectv current amplier system which includesy athird The input of this ampliier is connectedto. the variable contact of a voltage divider which.

tube 2l and an input circuit comprising a bias battery 22 and a movable contact point 23 which is part of a voltage divider 24.

The movable contact point 23 is controlled by a reversible motor 25 through a mechanical linkage 26. The reversible motor receives its power from an A. C. amplifier 2'I and a phase discrirninating stage 28. The input to these amplier stages comes from an inverter circuit which includes a set of contacts 36 driven by a coil 3l which is connected across the power lines IU. The inverter circuit also includes a filter circuit 32, a voltage reference battery 33, and a voltage divider 34 which is connected across the load terminals 35, 36. An ammeter 3I may be included in the circuit.

The operation of the circuit is as follows: Let it rst be assumed that the circuit is balanced, the input voltage is constant, and the output impedance does not vary. Under these conditions all the voltages are stabilized and the motor armature does not turn. The voltage drop from the contact point 38 to ground is equal to the Voltage of the reference battery 33. Since these voltages are equal, there is no tendency for current to flow between the contact points 3! when they are made, and as a result the input to amplier 2I is zero and the control electrodes of the tubes in stage 28 receive no added voltage.

AIn the balanced condition the voltage drop between contact point 23 and ground is substantially equal to the voltage of battery 22 and triode tubes 2l, 20 and I8 all pass a steady average current between their anodes and cathodes.

Now let it be assumed that the voltage of the supply lines I is increased by ten percent of thc normal value. This action causes the voltage across resistor I6 to be increased a like amount andthe potential of the anodes of triodes I'I has a tendency to increase and send more current through the triode anodes. However, the anodes are connected, through a high resistor, to the anode of triode I8 and the control electrodes of triodes II. The control electrode of triode I8 is connected to a voltage divider which is connected across the load terminals and, therefore,'the increase in supply voltage tends to increase the potential of this electrode. The increase in potential tends to increase the now of current through the anode'of triode I8 and reduce the potential of the control electrodes of triodes I8, thereby lowering the current through the series triodes and lowering the voltage across the load circuit.

From the above ana-lysis it will be evident that triode I8 has a regulating action all its own without using a voltage reference or standard. The amount of regulation available, however, is not sufficient to produce accurate results unless supplemented by other and more refined circuit elements.

An increase in potential on the supply lines I6 tends to increase the voltage drop across divider 24 and hence add to the voltage of bias battery 22 and raise the potential of the control electrode of ampliier triode 2|. This increase in voltage is transmitted through the amplifier stages by a decrease of potential of the control electrode of triode 28 and an increase of potential of the control electrode of triode I8. The result of the amplifier action is a decrease of the potential of the control electrodes of Vseries triodes Il and a consequent lowering of the voltage to the original steady state value at the load terminals 35. 36. y

The anode-cathode current of triode 20 passes through resistor 4I which is common to triode I8 and, therefore, a change in this current is applied to the potential difference between the cathode and control electrode Of triode I8.

The above described circuit (omitting voltage divider 34 and associated circuits) functions as an accurate voltage regulator and if the circuit constants associated with the direct current arnplifier remained constant over a long interval of time the circuit would no doubt be satisfactory for most classes of Voltage supply.

It is well known that direct current ampliers are subject to a variety of circuit variations which alter the overall gain and in the present application produce erroneous results. Changes in contact potential, changes in resistance due to ambient temperature changes, and changes in operating tube characteristics all produce a varying anode-cathode current in the output triode I8. These changes occur at a very slow rate and produce a gradual drift in output current rather than an abrupt change.

To compensate for the Vabove mentioned gradual drift in output current the additional control means is added to the circuit. Its operation may be described as follows: When the characteristics of the direct current amplifier changes to produce a different Voltage across the load terminals 35, 36, the condition is sensed by the circuit combination which includes voltage divider 34, battery 33, and contacts 38. When the voltage drop between contact point 38 and ground differs from the voltage of battery 33, a voltage difference is produced across open contacts 30, and when'the contacts are made a current pulse is produced which is applied to the input terminals of A. C. amplier 2l. The lter 32 prevents the pulse from travelling back to the load terminals 35, 35. The filter also prevents unwanted alternating components from entering the A. C. amplier.

The output of amplifier 21 is applied to the control electrodes of a pair of power triodes 42 and 43, the anodes of which are connected to the opposite ends of a secondary transformer winding 44. The primary winding 45, coil 3|, and windings 56 of motor 25 are all connected to the alternating power lines I8 and all receive vthe same frequency. During normal operation when the system is balanced no alternating voltage is impressed on the control electrodes of tubes 42, 43 and the current pulses through the tubes are equal.

The anode of one triode is positive when the other anode is negative and as a result each triode conducts only during alternate halves of the cycle. With no signal applied tothe control electrodes, the combined anode currents in conductor 56 produce a wave as shown in Fig. 3, having a frequency of cycles per second, similar to the output of a full wave rectifier. If the pulses are equal, no 50 cycle component appears in the output. However, when a 60 cycle signal from amplifier 2l is applied to the control electrodes of triodes 42, 3, the pulses through one triode are increased while the pulses through the other triode are decreased, thereby creating a 60 cycle component in conductor 50 as indi cated by the curve shown in Fig. 4. Depending upon the phase of the signal applied to the control electrode, the 60 cycle component is either in or out of phase with the line voltage. Since the direction of rotation of motor 25 is determined by the phase relationship between the currents in windings 48. and 47', the phase of' the; 6G. cycle component in the output signal from amplifier 27 controls the, direction of motor rotation. `Nindings di. are the usual split phase windings in seriesk with a large capacitor 48;, they are permanently connected-to power lines iii and always carry current.

The motor windings and, the transformer windings are connected so as to move contact point 23 (by means of mechanical coupling 26) toward the ground end of the voltage divider 24 whenever a changein the amplifier characteristics producesvtoo higha line voltage at the load terminals. When the. load voltage drifts toward alower value, contactpoint 23 is moved 'toward the negative end of thevoltage divider.

The partial circuit shown in. Fig. 2 is analternate connection which mayY beernployed to obtain the same result; In this circuit battery 2,21 is connected permanently to thepositive line conductor. Connections for the reference battery 33 and the` voltage divider 34 are the same as shownl in Fig. 1. However, the compensating effect, caused by motor 25 and delivered through the mechanical linkage 26, is applied to a contact point 5l on a resistor 52 which is inserted in the .cathode line of triode 2|. It is obvious that a. change in resistance value in resistor 52 produces a change in the control electrode potential ofA triode 2| in the same manner as a shift in contact point 23 on voltage divider 24. In all other waysthe circuits indicated by Figs. 1 and 2 are identical and function in the same manner to deliver a constant voltage to load 39.

While there have been described and illustrated specific embodiments of the invention, it will be obvious that various changes and modifications may be made therein without departing from the field of the invention which should be limited only by the scope of the appended claims.

What is claimed is.:

1. An electronic voltage regulator circuit cornprising, a source of direct current power, an electron discharge device connected in series aru rangement between the source and a load circuit, a voltage sensitive circuit connected across the load circuit for sensing a variation of load voltage, a direct current amplier for amplifying said voltage variations havingitsinput connected to the voltage sensitive circuit and its output connected to a control electrode in the series electron discharge device, an inverter for converting said voltage variations into a series of pulses, an electric motor with a mechanical connecting means for altering the characteristic of the direct current amplifier, and an alternating current amplifier with its input connected to the inverter and its output connected to the motor for amplifying the series of pulses and applying the amplified power to the motor to change the direct current amplifier characteristic.

2. An electronic voltage regulator circuit coinprising, a source of direct current power, an electron discharge device connected in series arrangement between the source and a load circuit and having a control electrode for varying the series impedance, a voltage sensitive circuit connected across the load circuit for sensing a variation of load voltage above or below a desired voltage value, a direct current amplifier for arnplifying said voltage variations having its input connected to the voltage sensitive circuit and its output connected to the control electrode in the series electron discharge device, an inverter for converting said voltage means for altering the characteristic' of the` direct current amplier, and an alternating cur rent amplifier with its input connected to they inverter and its output connected to the motor for amplifying the series of` pulses andapplying theampliiied power to the motor to change the across the load circuit for sensing'a variationl ofV load voltage above or below a, desired voltagev value, a: direct current amplifier foramplifying said voltage variations having its input connected to the voltage sensitive circuit and its output connected to the control electrode in the serieselectron discharge device, anv inverter for converting said voltage variations into a series of, pulses, a motor with a mechanical connecting means for altering the characteristic of the direct current amplifier, and an alternating current amplifier with its input connected to the inverter and its output connected to the motor for amplifying the series of pulses and applying the amplified power to the motor to change the direct current amplifier characteristic.

4. An electronic voltage regulator circuitcom-l prising, a source of direct current power, an electron discharge device connected in series arrangement between the sourceand a load circuit and having a control electrode for varying the series impedance, a voltage sensitive circuit including a voltage reference element connected across the load circuit for sensing a variation of load voltage above or below a desired voltage value, a direct current amplifier for amplifying said voltage variations having its input connected to the voltage sensitive circuit and its output connected to the control electrode in theseries electron discharge device, an inverter including vibrating contacts controlled by an alternating current supply for converting said voltage variations into a series of pulses the polarity of which depends upon the polarity of the variation of load voltage, a motor with a mechanical connecting means for altering the gain characteristic of the direct current amplifier, and an alternating current amplifier with its input connected to the inverter and its output connected to the motor for amplifying the series of pulses and applying the amplied power to the motor to change the gain of the direct current amplifier.

5. An electronic voltage regulator circuit comprising, a source of direct current power, an electron discharge device connected in series arrangement between the source and a load circuit and having a control electrode for varying the series impedance, a voltage sensitive circuit including a voltage reference element connected across the load circuit for sensing a variation of load voltage above or below a desired voltage value, a direct current amplifier for amplifying said voltage variations having its input connected to the voltage sensitive circuit and its output connected to the control electrode in the series electron discharge device, an inverter including vibrating contacts controlled by an alternating current supply for converting said voltage variations into a series of pulses the polarity of which depends variations; into a. series: 0f pulses, amotor with aA mechanicalconnecting.:

upon the polarity of the variation of load voltage, a two-phase motor having a rst set of coils connected to the alternating current supply and having a mechanical connecting means for changing the output amplitude of the direct current ampliiier, and an alternating current ampli-er with its input connected to the inverter and its output connected to a second of coils in the two-phase motor for amplifying the series of pulses and applying the amplied power to the motor to change the output amplitude of the direct current amplifier.

6. An electronic voltage regulator circuit comprising, a source of direct current power, an electron discharge device connected in series arrangement between the source and a load circuit and having a control electrode for varying the series impedance, a voltage sensitive circuit including a voltage reference element connected across the load circuit for sensing a variation of load voltage above or below a desired voltage value, a direct current amplier for amplifying said voltage variations having its input connected to the voltage sensitive circuit and its output connected to the control electrode in the series electron discharge device, an inverter including Vibrating contacts controlled by an alternating current supply for converting said voltage variations into a series of pulses the polarity of which depends upon the polarity of the variation of load voltage, a two-phase motor having a rst set of coils connected to the alternating current supply and having a mechanical connecting means for changing the output amplitude of the direct current amplier, and an alternating current amplier and phase discriminator with its input connected to the inverter and its output connected to a second set of coils in the two-phase motor for amplifying the series of pulses in their proper phase relation and applying the amplified power to the motor to change the output amplitude of the direct current amplifier and thereby eliminate the variation of load voltage.

7. An electronic voltage regulator circuit comprising, a source of direct current power, an electron discharge device connected in series arrangement between the source and a load circuit and having a control electrode i'or varying theseries impedance, a iirst voltage sensitive circuit includ- 8. ing a voltage reference element connected acrossthe load circuit for sensing a variation of load voltage above or below a voltage Value, a second Voltage sensitive circuit also including a voltage reference element connected across the load circuit for sensing a variation of load voltage above or below a desired voltage value, a direct current ampliiier with its input circuit connected to said first voltage sensitive circuit and with its output circuit connected to the control electrode in the series electron discharge device, an inverterconnected to the second voltage sensitive circuit and including vibrating contacts controlled and operated by an alternating current supply for converting said voltage variations into'a. series of pulses the polarity of which depends upon the polarity of the variation o load voltage, Va twophase motor having a rst set of coils connected to the alternating current supply and having a mechanical connecting means for changing the output amplitude of the direct currentarnpliiier, and an alternating current amplier and discriminator with its input connected to the inverter and its output connected to a second set oi coils in the two-phase motor for amplifying the series of pulses in their proper phase relation and applying the amplied power to the motor to change the output amplitude of the direct current amplier and thereby eliminate the Variation of load voltage as sensed by the second voltage sensitive circuit.

FRANK J. LUPO.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 2,373,208 'I'rucksess Apr. 10, 1945 2,389,364 Jenks Nov. 20,1945 2,447,321 Ertzman Aug. 17, 1948 2,519,377 Jenkins Aug. 22, 1950 2,535,355 Froman Dec. 26, 1950 2,563,179 Malsbary Aug. 7, 1951 FOREIGN PATENTS Number Country Date 472,326 Great Britain Sept. 22, 1937 

